Correct Response: D. The Atlantic Ocean formed as a consequence of the breakup of Pangaea. The breakup occurred in several stages over millions of years, beginning 175 million years ago in the Middle Jurassic. Pangaea began to break into separate continents as a consequence of geologic rifting of continental crust. The rift developed into a divergent plate boundary that pushed the plates apart, eventually forming the Atlantic Ocean basin. Erosion caused by continental glaciations (A) is not a process capable of initiating the formation of a major ocean basin and no continental glaciations occurred during the Middle Jurassic. Subduction (B) occurs along convergent plate boundaries and could not have initiated the formation of the Atlantic Ocean basin. The development of a syncline to explain the initial formation of the Atlantic Ocean basin (C) is not consistent with modern plate tectonic theory.
